I guess this is part of it. I live in Colorado. It's easier to get a worthwhile elk tag than a good deer tag. I've seen them shot with everything from .243 up, and shot them myself with a range of calibers from 6.5 to .458. Most years I get an elk, and I've had camp and family members shoot a lot more. I've got a pretty good idea of what works and what doesn't. If you put an expanded bullet through both lungs and/or the heart of an elk, it will drop. They don't have any spares hiding anywhere. In order to do that, you have to place your bullet in the right place, and it has to have enough sectional density and weight retention to get there. There's nothing magical about it. Things I've learned:
- The high sectional density calibers (6.5mm, 7mm, .338) do better than the low sectional density calibers (.224 (I hate this is now legal), .243, .257, .270 and anyone using light-for-caliber stuff). The .308 cartridges are a special case, because high-SD bullets are available, but few people use them.
- You want an exit wound for tracking, because there's NOTHING you can do to guarantee a bang-flop. The one I shot with the .45-90 (400gr. Hawk) I got both lungs and the heart dead on. It went 75y in dense timber, dropping it's blood supply out the exit wound as it ran.
- Frangible bullets result in lost elk due to failing to reach the heart & back lung. Leave your SMKs, Scenars, A-Maxes and Bergers at home please. I would also avoid the Ballistic Tip. Weight retention is your friend.
- Cup & core bullets are OK if they hit at the right velocity, but bonded/partitioned have a much bigger velocity window and the cost difference is trivial
- Copper bullets work OK and have lots of penetration, but the wounds tend to be small and the animals don't drop fast. I don't use them personally.
- Impact velocity and frangibility increase the chance of a bang-flop. But frangibility also increases the chance of a lost elk, so velocity is your best bet to get them down fast. It's more important to have easy tracking than to gamble on no tracking.
- Most hunters underestimate the downsides of rifle weigh. The places the elk are are hard to get to.
- Hunters with big magnums miss a lot unless the practice a lot. Your average hunter has no business shooting a .300 or .338 WM.
It's kind of funny, because some outfitters will really play up the durability of elk to absurd levels. I guess it makes the whole things seem like a manly man hunt. I got a good chuckle out the the quote about elk being "thick skinned" a few pages back
Skin one elk, and you'll realize how silly that is.
I have exactly zero doubt a .264 with 160 Weldcores will work fine for elk, and won't require waiting for any magic shot angles.